The determination of radionuclides at environmental levels using classical radiometric counting is well established and likely to remain the method of choice for short half-life species. However, innovations in analytical instrumentation in the last ten years have the potential to replace radiometric counting for a wide range of longer half-life species.
Elemental and isotopic analysis has advanced significantly with the introduction of plasma source mass spectrometry. A variety of plasmas have been used as ionization. sources, e.g., glow discharges, microwave induced plasmas, but the inductively coupled plasma (ICP) is the most widely accepted, and de facto, the preferred ion source for atomic mass spectrometry. The inductively coupled plasma is compatible with solid, liquid or gaseous sample introduction and is a robust and efficient ionization source for atomic mass spectrometry.
For some potential applications of plasma mass source spectrometry, e.g., environmental and biomedical monitoring of radioisotopes, current techniques may not possess the required detection limits or selectivity. Classical radiometric techniques may provide the required detection limits, but do so at the expense of protracted count times and extensive sample preparation and clean-up. For example, within a plutonium bioassay program, current radiometric methods offer detection limits of 500 μBq per litre, but require 1-2 days of sample preparation and radiometric count times of, e.g., four days with α-spectrometry and up to 28 days for α-track counting. there is a requirement to develop plasma source mass spectrometry to provide enhanced selectivity and improved detection limits without sacrificing the inherent flexibility, repidity and robustness of the technique.